The Aloe plant is an intricate plant which contains many biologically active substances. (Cohen et al. in Wound Healing/Biochemical and Clinical Aspects, 1st ed. W B Saunders, Philadelphia (1992)) Studies have shown that the majority of these biologically active substances are located in a clear gel fillet located in the center of Aloe leaves. Historically, Aloe products have been used in dermatological applications for the treatment of burns, sores and other wounds. These uses have stimulated a great deal of research on identifying compounds from Aloe plants that have clinical activity, especially anti-inflammatory activity. (See, e.g., Grindlay and Reynolds (1986) J. of Ethnopharmacology 16:117-151; Hart et al. (1988) J. of Ethnopharmacology 23:61-71) As a result of these studies there have been numerous reports of Aloe compounds having anti-tumor, anti-gastric ulcer, anti-diabetic and anti-tyrosinase activity. (See, e.g. Yag et al. (1977) Z. Naturforsch 32c:731-734).
The anti-inflammatory activity of Aloe compounds has been extensively investigated. Studies by Davis et al. have shown that Aloe not only reduces inflammation, but also improves wound healing. (Davis et al. (1994) J. Am. Podiatric Med. Assoc. 84:77-81, Davis et al. (1989) J. Am. Podiatric Med. Assoc. 79:395-397). The anti-inflammatory/wound healing ability of Aloe has been attributed to a growth factor-like substance that activates the wound healing and inflammation reduction processes. (Davis et al. (1994) J. Am. Podiatric Med. Assoc. 84:77-81, Davis et al (1989) J. Am. Podiatric Med. Assoc. 79:395-397).
Despite the great deal of activity that has taken place in this area, to date, there have been no reports on the possible presence of antioxidants in Aloe plants and their physiological effects in biological systems. Naturally occurring antioxidants are primarily polyphenolic compounds, many of which are found in plants. Phenolic antioxidants have been found to function as free radical terminators and metal chelators. They are primarily used as food additives and nutritional supplements. A great deal of research has been conducted to identify naturally occurring phenolic antioxidants. Examples of some common plant phenolic antioxidants include flavonoid compounds, cinnamic acid derivatives, coumarins, tocopherols, and polyfunctional organic acids. Some of these compounds, including flavanols, Schisanbanol and Schizandrin B, are now commercially available. See, e.g., Bors and Saran (1987) Free Rad. Res. Comms. 2:289-295, Robak and Gryglewski (1988) Biochem. Pharmacol. 37:837-841, Das and Ratty (1986) in Plant Flavonoids in Medicine: Biochemical, Pharmacological, and Structure-Activity Relationship (Cody, Middleton, and Harborne, (eds)) Alan R. Liss, New York, Laughton et al. (1989) Biochem. Pharmacol. 38:2859-2867, Xue et al. (1992) Free Rad. Biol. Med. 12:127-135.